Mexico's original take-out food, tamales (singular: tamal) developed in pre-Hispanic Mexico and became more sophisticated with the Spanish introduction of pork and other ingredients. Today, tamales show up as both walk-away snacks and elaborate fiesta delicacies, and like all Mexican cuisine, they vary widely by region and family tradition. The most popular rellenos (fillings) are pork and cheese, but might be anything from fish to iguana, augmented by pumpkin, pineapple rice or peanuts, and tucked into a blanket of yellow, black or purple corn dough called masa. They may be baked, steamed or grilled in a jacket of dried corn husks or fresh corn or banana leaves. Sometimes tamales are even wrapped in palm, avocado or leaves of chaya (a spinach-like vegetable).